Document N2zYZ9nxQ4G4bRkMORonMZ2Eb

FILE NAME: Oil Industry and American Petroleum Institute (API) DATE: 1937 July DOC#: API101 DOCUMENT DESCRIPTION: Report, Standard Oil Co. - Dust Producing Operations in the Production of Petroleum Products and Associated Products t :s' a y.* . ** - -, - v . v .. ..- .j^ ^ ^ S i ^ J A ^ D A R D ^ .Q jE ^ C O M P A N Y :f N. ':J v: ^ > r - .>..T l - 3 0 ' . R n r K F r n i- r p : - o r a 7 a -.": ^ ... ,-. ir^. *ry..' .v-5 ,:;JULY.-.!9 3 7 ' ' .^4 * r s J ^ r^ 'i ' f * PAW7 ^ r " M'3 b u l l e t in may as; du plica ted o r u s l .'Shec *R '/'*> /' * 'rZv~<' *- _ . * >- 7-. ~ - * " ' ' ' ` W IT H O U T w P 'T T n P f t u ;l5 iO fM . '*#' aJ'i I |l H.U- , , . *v<.7?. Up t? ifar,- *lic -Ss5iiW* --*^,.-`.T1r'J . 3 Ci KVTT gs*^.-:. * MEDICO - SAFETY MEMORANDUM d u st producing operations in th e pro d u ctio n of petro leum pro d u cts A N D ASSOCIATED ACTIVITIES CONTENTS PAGE INTRODUCTION PART I - DUST AS A HEALTH HAZARD ' t I - WET IS THE DUST PROBLEM SO IMPORTANT?.............................. II - WHAT IS MEANT BY "DUST"?............................................ III - WHAT ARE THE PHYSIOLOGICAL EFFECTS PRODUCED BY The Inhalation of Dust........................................... Silicosis in General......................................... ' First National Silicosis Conference.......................... Silicatosis.................................................. Asbestosis................................................... 17 - WHAT IS THE MAXIMUM PERMISSABLE DUST CONCENTRATION? Formula For Determining MgJdmum Permissible Concentration of Silica in The Air Breathed................................... Safe Dust Concentrations, Impringer Samples...................... V - HOW NAY THE CONCENTRATION AND CHARACTER OF INDUSTRIAL DUSTS BE DETERMINED?............................................... -, The Impinger Apparatus........................................... The Zeiss Konimeter.............................................. The Bausch & Lamb Dust Counter................................... ,, 2 2 3 4 4 5 7 7, 8 9 9 10,11 11 11 PART II - D U ST PRODUCING OPERATIONS STUDIED WHAT ARE THE PRINCIPAL DUST PRODUCING OPERATIONS? I - SAND-BLASTING....................................................... 13-15 II - FILTERING OPERATIONS............................................ .... 15-27 A - Filter Clay or Fullers Earth: What is Filter Clay or Fullers Earth?........................ How is Filter Clay Mined and Prepared?....................... How is Filter Clay Used?..................................... "Burning" Clay............................................ Charging Filters.......................................... Dumping Filters............. Composition of Filter House Air Borne Dust................... Control of Filter Clay Dust................................ 15,16 16,17 17,18 18,19 19,20 20,21 21 22 B - Contact Clay: Main Constituents of Contact Clays........................... What is "Filtrol" and How is it Produced?................... What is the Chemical Composition of Filtrol?........... ..... 22,23 23,24 9*' -2- PAGE C - Bone Black or Charred Bone; How is Bone Black Used...................... .............. . 26 INSULATING OPERATIONS; A - What Physiological Reactions are Provoked by ' Insulating Materials?.... ........................... . 27 B - What Are The Principal Insulating Operations and How Much Bust is Produced During Such Operations?. Insulating 12" Steam Lines..................... Insulating a 750-Pound Cracking Coil Accumulator Insulating Treating Plant Acid Suction Line..... Insulating Cracking Coil Hot Oil Lines.... . Dismantling or Removing Old Insulation.......... Crushing Scrap Asbestos...... ........... Crushing Old Cork Insulation............... . 27 27.28 . 28 *' 28 28 28.29 29 29 GUNITING OPERATIONS: What Is Gunite and How.Is It Applied?....................... Removal of Gunite Lingins........................... ........ 29,30 30 WELDING AND CUTTING OPERATIONS; A - Welding Operations: 1. Electric Arc Welding................... ................. 30 What are Coated Electrodes?........................... 30,31 What do These Electrodes Contain and What Products Result From Their Use?......... ......... 31,32 What is The Amount and What Are the , ' Characteristics of Fumes or Dust Produced By The Various Electric Arc Welding Operations...... 32-35 What Physiological Effects on Welders is Produced by The Use of Coated Electrodes..... ....... 35-37 2. Oxy-Acetylene Welding................................... 37 Fumes or Dust Produced by Oxy-Acetylene Welding.... . 37 ^ - Burning or Cutting Operations: 1. With Oxy-Acetylene,........................... Fumes or Dust Produced by Oxy-Acetylene Burning......... 2. With Natural Gas......................................... 37,38 _ 38 38 C -- Health Hazards Produced by Welding and Cutting Operations.... 38 RINDING OPERATIONS: What is The Composition of Grinding Wheels?................. Is Abrasive Dust Harmful?................................... 39 39,40 1 - What are the More Freauentlv Used Tvpes of Grin^*-* t-2- PAGE C - Bone Black or Charred Bone; How is Bone Black Used.............................. ....... . . 26 III r INSULATING OPERATIONS; A - What Physiological Reactions are Provoked by ` Insulating Materials?....................................... 27 B - What Are The Principal Insulating Operations and How Much Dust is Produoed During Such Operations?.........., 27 . Insulating 12" Steam Lines................................ 27,28 Insulating a 750-Pound Cracking Coil Accumulator......... 28 Insulating Treating Plant Acid Suction Line...... ........ 28 Insulating Cracking Coil Hot Oil Lines............ . 28 Dismantling or Removing Old Insulation...... ............. 28,29 Crushing Scrap Asbestos................................... 29 Crushing Old Cork Insulation.................... ........ . 29 XV ,, GUNITIMG OPERATIONS; What Is Gunite and How Is It Applied?........................ 29,30 . Removal of Gunite Lingins............... '.................... 30 V - WELDING AND CUTTING OPERATIONS; A - Welding Operations; _ .. 1, Electrio Arc Welding.............. ................... . 30 What are Coated Electrodes?................. .......... 30,31^ What do These Electrodes Contain and What > Products Result From Their Use?.................... . 31,32 What is The Amount and What Are the ' Characteristics of Fumes or Dust Produced By The Various Electric Arc Welding Operations...... 32-35 What Physiological Effects on Welders is > Produced b*y The Use of Coated Electrodes............ 35-37 2. Oxy-Acetylene Welding................................. 37 Fumes or Dust Produced by Oxy-Acetylene Welding....... 37 B - Burning or Cutting Operations; 1. With Oay-Acetylene....................................... Fumes or Dust Produced by Oxy-Aoetylene Burning......... 2. With Nt'.rural Gas......................................... 37,38 38 .38 C - Health Hazards Produced by Welding and Cutting Operations.... 38 VI - GRINDING OPERATIONS; What is The Composition of Grinding Wheels?................. Is Abrasive Dust Harmful?.................................... 39 39,40 1 - What are the More Frequently Used Types of Grinders. Character of the Dust they Prod ice?.'....... 40 -3- A - TANDEM FLOOR TOCL GRINDERS................................... Dust Produoed by Tandem Floor Grinders..................... B - TANDEM BENCH GRINDERS........................................ Dust Produced by Tandem Bench Grinders..................... Characteristics of Dust Produced by Tandem Bench Grinders............................................ C - SINGLE FLOOR TOOL GRINDERS.................... Dust Produoed by Single Floor Grinders..................... Characteristics of Dust Produoed........................... D - UNIVERSAL GRINDERS.......................................... Dust Produced By Universal Grinders......................... Charaotersitics of DustProduced............................ E - SURFACE GRINDERS............................................ Dust Produoed by Surfaoe Grinders........................... F - LANDIS TOOL GRINDERS........................................ Dust Produced by Landis ToolGrinders........................ G - YANKEE DRILL GRINDER........................................ Dust Produced by.Yankee Drill Grinder...................... H - AUTOMATIC CIRCULAR SAW SHARPENING MACHINE................... Dust Produoed by Yankee Drill Grinder...................... I - AUTOMATIC BAND SAW GRINDER.................................. Dust Produoed by Automatic Band Saw Grinder................ J - AUTOMATIC BAND SAW LAP GRINDER.............................. Dust Produoed by Lap Grinder............................... K - PLANING KNIFE BLADE GRINDER......... ........................ Dust Produced by Blade Grinder............................. L - LINDERMAN CUTTER GRINDER.................................... Bust Produoed by Cutter Grinder............................ M - GANG SAW BLADE GRINDER...................................... Dust Produoed by Gang Saw Blade Grinder.................... N - EDGER SAW GRINDER........................................... Dust Produced by Edger Saw Grinder......................... 0 - CIRCULAR SLAB CUT-OFF SAW GRINDER........................... Dust Produced by Cut-Off Saw Grinder....................... P - "HOG KNIFE" GRINDER......................................... Dust Produced by "Hog Knife" Grinder....................... Q - CUTTER GRINDER.............................................. fhiR-h tv* >vv OvH-.ftr C,rinH tv .____ . PAGE 40,41 41,42 41 41 42 43 43 43 44,45 44 45 45 45 45,46 45 46 46 46 46 46,47* 47 47 47 4f 47 47 47 47 47 47 47 47,48 48 48 48 48 * ~ -4- PAC-E Control of Dust from Grinding Wheels........................... 48 h a n d l i n g POWDERED OR PULVERIZED MATERIALS: A - LIME: . (l) Hydrated Lime............................................ 49,50 (2) Lump Quick Lime.......................................... 50,51 What Physiological Effect is Produced by Lime Dust.......... 51 B - METALLIC ZINC DUST: . Typical Screen Analysis...................................... 51 Dust Produced............................ 51 - What Physiological Effect is Produced by Zinc Dust;........ . 51 C - ASBESTOS "FLOAT": ' Dust Produced................................................ .,,.Physiological Effect of Asbestos Particles................... 51,52 52 D - GROUND MICA: Dust Produced.......... 52 Physiological Effect of Mica Dust............................ 52 ...... . E - SULPHUR: ' (l) Sulphur Flour.................. (2) Crude Sulphur............................................ Physiological Effectof Sulphur............................... 52 52,53 53 `F - LITHARGE: Dust Produced................................................ Necessary Precautionary Measures When Handling Litharge................................ .......... 53 5&, 54 G - SODA ASH: ' ' Dust Produced......... ............................... ...... 54,55 H - TALC or "SOAPSTONE": .. . > Dust Prodused........................................... 55 Physiological Effeots Produced by Talc Dust..... ............ 55 I - GRAPHITE: . Dust Produced.......... ................................ ...... 55,56 . J - SLATE FLOUR: ' Dust Produced............................................. 56 Effect of Slate Flour on the Lungs........................... 57 K - GRINDING DERRIS ROOT: ' Dust Produced............................................... 57 To What Extent is Derris Toxio?.............................. 57 L - GRINDING PYRETHRUM FLOWERS: Dust Produced................................... 57,58 M - MIXING AND PACKING "FLIT" POWDER: -5- ;IXANING TUBES AND DRUMS; CRACKING COIL SOAKING DRUMS; Dust Produced*........... _ CRACKING COIL TUBES: Dust Produced.... .J H .. WATER HEADERS AND BOILER TUBES: . >. ,*** Dust Produc ed.............. . Composition of Dust from Front Water Wall Eeader............. f+Z'i FOINDRY OPERATIONS; -> r>*-t JA K . % 21 9: J A - POURING MOLTEN METAL INTO SAND MOULDS.... B - "SHAKING OUT" CASTINGS.................. (j - CLEANING CASTINGS: (a) Preliminary Cleaning.............. (b) Tumblast.......................... (c) Sly Tumbling Mill................. (d) Tumbling Barrels.................. (e) Air-Blasting...................... (f) Rough Snagging Wheels............. (g) Fine Snagging and Polishing Wheels. (h) Cone Grinding Wheels.............. Average Dustiness of Cleaning Room Air. D - CORE MAKING............................. E - SEPARATION OF BRASS FOUNDRY SKIMMINGS___ - MASON1S OPERATIONS: I D ii hi IY Y YI - TEARING OUT STILL FIRE BOXES...... - CHIPPING OR CUTTING CONCRETE...... - CHIPPING MORTAR FROM BETWEEN BRICK. - CRUSHING FIRE BRICK............... - SHAPING FIRE BRICK ON EMERY WHEEL.. - '^DISMANTLING MASONRY............... H - WOODWORKING OPERATIONS; A - BOX SHOOK MANUFACTURE J (&) Resawing.................. (b) Ripsawing................. (c) Cut of Sawing............. (d) Planing................... f Dustiness of Shook-Factory Air. B - BELT SANDERS, SAND DISCS AND SPINDLES OR CYLINDERS: (a) Belt Sanders... J....................................... (b) Sand Discs or Wheels........................... ........ (c) Sand Spindles or Cylinders.............................. C - MAKING WOODEN CRATES: (a) Band Saws...... , (b) Railroad Saws.... 58,59 59 59 60 60,61 61 61 61,62 62 62 62,63 63 63,64 64 64 64,65 65 65 65 65,66 66 66 66 67 67 67 S'7,68 68 68 53,69 59,70 70 70 'S'?/: ''iI'Tf.' ZI il If fl l j.- 'i K* i' ll ' ti f I[fi'J -. i :{!: ' 1; . Ifi: , t ! 1 ,:a i . d ! I -6- ROCK EXCAVATION: A - DRILLING.................................................. B - 3LASTING.................................................. C -MUCKING..'.................................. T.............. D - DUST CONTROL MEASURES: (a) Wet Drilling and Wetting Down Rock Walls and Muck Piles......................................... (b) General Ventilation.................................. (c) Dust Exhaust Hoods on Drills and Other Mucking Operations and LocalSources of Dust.............. (d) Personal Protection by Means of Respirators and Positive - Pressure Masks....................... PAGE 70 71 71 71 71 71,72 72 PART III - M EASURES FOR REDUCTION OF THE D U ST HAZARD HOW CAN THE DUST HAZARD BE REDUCED? SJ . I ' 1 ] rrj A - DESIGN PLANT FOR DUST CONTROL........................... 74 B - PROVIDE BUILDING VENTILATION............................ 74 C - STORE DUSTY MATERIALS IN DUST-TIGHT BINS............... 74 D - ENCLOSE MATERIAL HANDLING EQUIPMENT.................... 74 E - ISOLATE DUSTY PROCESSES................................. 74 F - PROVIDE WET METHODS OF OPERATION........................ 74 G - DESIGN EQUIPMENT TO CONTROL DUST....................... 75 H - PROVIDE EXHAUST SYSTEMS................................. 75 I - ESTABLISH MAINTENANCE AND GOOD HOUSEKEEPING PROCEDURE... 75 J - PROVIDE RESPIRATORS..................................... 76 (a) Air Purifying Types qf Respirators.................. (b) Supplied Air Respirators............................ The Air Line Respirator........................... Abrasive Blasting Respirator...................... (c) Acceptance and Use of Personal Respiratory Protection by Workmen............................ (d) Use, Maintenance and Care of Respirators............ 76,77 77 73,79 79 79,30 30 ** WHAT MEDICAL CONTROL SHOULD BE EXERCISED IN THE SELECTION AND SUPERVISION OF MEN WORKING ON DUSTY JOBS?................ 30,31 PHYSICAL EXAMINATIONS................................... 30 DESIRABLE PHYSICAL QUALIFICATIONS...................... 31 RE-EXAMINATIONS......................................... 31 T H E LIMITATIONS ONCLUS ION........................ .......................................... 31,32 -7- to silicate dust. 0* * f<flatosla - According to authorities oited pj^-Drinker & Hatch in their book 1 Dusts", the pathology produced by asbertos'.-is not like that of silicosis. Gardner of Saranao Lake is of the opinion.that the asbestos fibers group U nook of an alveolus and shut it off, causing^what is known as "Atelectasis", is no definite migration or transportation of.the dust particles to the lymph #s and no fibrous n___o__d_)u. .l1 e_s_. AA-s . -tVh, .e atelectatic are_a__s__'_' ii_n__c___r__e___a__s__e__J.1the reductionJ _in area oauses serious dyspnea or laborered breathing,'. Dr. A. J. Lanza (U. S. Health ***: 50j 1 - 1935) suggests that the enlarged heartsvnoted frequently in his fl.*^f"seoond stage Asbestosis may be due to the increased load on the heart. It ves"ttore work to pump blood through the fibrosed than*.''through the normal lung. Re- (t."pathological studies from human lungs from oases of asbestosis'have indicated a *ffuse typo of interstitial fibrosis with a certain amount of emphysema. I* - WHAT IS THE MAXIMUM FERMISSABLL DUST CONCENTRATION? - Thoro appoars to be a ido variation in the maximum concentration of dust which might be inhaled without Ubsequent injury to workmen. Some dusts (as lead) are determined by chemical Wthods and the concentrations in air are recorded gravimetrioally as milligrams per ihio meter. However, bHe available information on the amount of lead dust that is ^jmful and the methods of determining lead are better and more acourate than those T^. silioa dust. It is rather well.agreed that an intake of about 1.5 milligrams o f ': Jad a day, whether this is aoquired by breathing dust or b y drinking water that con tains lead, is the maximum allowable quantity. Others (as silica, where site is a Saotor in determining dangerous particles), are othod tells the whole story, but in both oases formation neoessary for the purpose. usually given by count. Neither it may be possible to secure the in The maximum silioa dust concentration considered permissible in the air breath ed by & workman at any point in the normal breathing zone has not been definitely es- :ablished. There is considerable differenoe of opinion regarding the- range of par- tides that are oounted when using the Publio Health Service technique and light ..field illumination. Bloomfield of the United States,Publio Health Service and B r o w n ' of the United States Bureau of Nines contend that they oount particles from one mi- -pron and upward, or- even 0.7 mioron and upward. The Industrial Commission tonsin and its Advisory Committee, oomposed of both employers and scientists* ___ . ever, agreed in 1932 on a tentative figure of 15 million oountable particles under * V / rtV' i0 aiorons in longest dimension with free silioa oontent of 35 per oent in a cubio V oot of air as determined b y United States Publio Health Servioe technique. Varia- ' |J Jr ions in fr63 silioa oontent will make proportional inverse ohanges in this standard. la the case of practioally pure silioa, the permissible dust oount should probably ^Tnever exoeed 5,000,000 oountable partioles. By oountable partioles is meant those {Jj!1** .Jpartioles between 0.5 to 10 microns in the longest dimension. Particles of this * ? I* size are the ones that are believed to cause the greatest damage and form no visible oloud. Dust partioles smaller than 0.5 miorons in the longest dimension are not {ordinarily oountable. Dust partioles larger than 10 miorons in longest dimension do not ordinarily reach parts of the lung where they can produoe injury of a respira tory nature. Most industrial dusts have but few partioles above two or three mi * J crons in size. They are usually about 90 to 9B per oent. below two or three microns jand~50 per oent. below about 0.5 to 0,7 microns. A n exception to this would be a . dust sample taken close to the point of generation of dust and before the larger partioles had time to settle out of the- air. In South Afrioa the figure is 1 milligram per oubio meter (or 300 particles per cubio oentimeter, or approximately 8,5 million per oubio foot. ) Dr. Lanza found jin 1917 in the Joplin, Missouri district that with good engineering practice, a J figure of 1 milligram per 100 liters of air could be attained. This value attribute d + T . - r . . . . n r , . . - . +- Viw w in eonmari son with the South African standards. As there -27- .flb. Ill - INSULATING OPERATIONS Insulation plays an important part in the prooessing of petroleum products. two types of insulating material most frequently used are "Sponge Felt" (asbeB- ground sponge to give dead air space and thus increase the effectiveness iva insulation) and a mixture of 85# magnesia and 15# asbestos. Rock wool is m .o a considerably lesser degree. In the ordinary commercial form, Rock Wool, od at our refineries, does not present a dust hazard. It .is also used for j insulation, and is available in small nodule form which can be blown into gfc- "85# magnesia" is a mixture of magnesia and granulated asbestos and pressed, - ^ b l o c k s of various sizes and shapes (usually 16" x 18" x l-l/2"). The most dust ft*0111 dismantling old insulation and grinding scrap material for use as a plaB"ganlster". The average service of men engaged in insulating operations is ' fifteen years. Most of these men have been transferred from the Common Labor ^rtaent. They work nine out of fourteen eight-hour shifts, in gangs of from two men, and are actually exposed to dust for less than sixty per cent, of their W k i u g time. Goggles are sometimes provided, and occasionally MSA "Camfo" Respira- but this equipment is not used as muoh as it should be. Generally speaking, ibut 85# of their work is with sponge felt and 15# with 85# magnesia insulation. of the larger southern refineries about 300,000 square fee of sponge felt nd 'o'OOO square feet of 85# magnesia are handled a year. ^ What Physiological Reactions are Provoked by Insulating Materials? According _T,Dr. Leroy U. Gardner (Joum. Indust, Hyg,Mar. 1937,Vol. 19, No. 3, P.121) asbestos dust its fibrous particles does not seem to be readily handled by the protective jsobanism of the lungs. Quoting from his article "They are not removed to the lymphoid tissue but remain in contact with the delicate walls of the air spaces. They become surrounded by an iron-oontaining ooating that fraotures and gives rise to the pecu liar structures known as 'asbestosis bodies'. The fibers are irri tating, perhaps because of their form, and they excite a fibrosis which begins about the terminal bronchioles and spreads to form dif fuse patones in the parenchyma. Often the distribution is sub-pleural. In the presence cf infection, the reaction tc asbestos dust is much mere- severe than that caused by the dust alone." * There is nothing in the pertinent literature, nor does the Bureau of Mines know of any evidence, which would demonstrate magnesite (a natural magnesium carbon ate) to be harmful. It would fall in the class of "nuisance dusts" such as gypsum. While many of the so-called "nuisance dusts" have never been found to be harmful, it isythe opinion of most investigators in the field of industrial hygiene that no work er should be exposed to any dust in a concentration exceeding 75 or 100 millions of particles per cubic foot of air. . 'f B - What are the Principal Insulating Operations and How Much Dust is. Produced During s-uoh Operations? There Is, of course, a wido variation in the amount of insu lation work and the amount of dust produced. A few examples, however, will give a good general idea* Bv INSULATING 12" STEAM LINES 6" x 18" x l-l/2" blocks of 85# mag nesia are tied on the steam line with 14-gauge galvanized wire and covered with roofing paper to make it waterproof. Often times this work is performed on scaffolds twelve to fifteen feet above the ground, i*unini jider&ble dust (as high as 18,124,800 particles of less than ten ** eroas per cubic foon) results from tapping the blooks into place. jjTmplos taken during the entire operation had an average concentra tion of 6,881,760 particles per cubic foot. About 90# of these dust a -articles were slightly angular, crystalline in appearance and above five microns or less- in sire (as seen under the Konimeter Microscope)) 5^ wexe rounded opaque, ten microns or more in size; and 5# were opeque scale-like, five microns or more in size. Samples taken while applying asbestos sponge felt to a 12" steam line had a dust concen *=i tration as high as 23,788,800 particles of ten microns or less in si* Per cubic foot. The average was 12,574,080 particles per cubic CR foot. These dust concentrations are considered too high for work ing without adequate protection. cm INSULATING A 750-POUND CRACKING COIL ACCUMULATOR: 6" x 36" blocks I of Johns-Manville "Fire Felt" are first applied and plastered with B=? extra AA Rubberoid Asbestos Cement and waterproofed with Johns- . Marrvill "Insulkote". The dustiness of handling these materials has Jp 'been considerably reduoed since the manufacturers began shipping the "Fire Felt" in cardboard cartons containing thirteen or twenty CS blooks, and the plaster in hundred-pound paper bags. Samples taken 'during this operation had an average dust concentration of 4,502,880 particles, ten microns or less in sice per cubic foot. About 75# of C r these dust particles were slightly angular in appearance, five mi- C ^orons or less in sicej 10% were scale-like; opaque; and 15% were ' '.rod-like and fibrous. 5C nm INSULATING TREATING PLANT ACID SUCTION LINEu Seotions of "Sponge Felt Pipe Cover" are cut to fit pipe lengths with an ordinary carpen ter's hand saw. This operation produces on an average 821,280 par 6? ticles of dust, ten microns or less in sice, per cubic foot. Under '"the Konimeter Microsoope all of these particles are slightly angular, ^ crystalline in appearance, and five microns or less in size. The blocks or sections of the pipe oover are held in place by wrapping si $16 gauge galvanized wire about each one. INSULATING CRACKING COIL HOT OIL LINES: All hot oil lines at crack ing coils are insulated with 2" asbestos tubing (55% magnesia and 15# asbestos) held in place by fine copper wire. Sections of the tubing are cut to fit particular areas by means of an ordinary carpenter's hand saw. This produoes 7,788,000 particles of dust, ten microns or less in sice, per cubic foot. Under the miorosoope, SO# of these C dust partioles appeared to be rounded crystalline and about three mi . crons or less in sice. Each section of tubing is pounded into place with the open hand so that it fits snugly against the pipe, and then wired into position. The dust produced from both of these operations averages about 3,379,520 particles per cubic foot. Under the micro scope, approximately 80# or 90# of the dust particles appear crystal line, more or less angular, and five microns or less in sice; the re maining 10# or more are rounded in appearance, and over ten microns in sice. DISMANTLING OR REMOVING OLD INSULATION: As a general rule, the dismantling or removal of old insulation is a more dusty operation * than the application of new insulation. The old insulation is chopped or cut with a hatchet or small hand-axe, and pried loose and pulled off with the hands. This produces dust concentrations as high as 5,890,560 particles, ten microns or less in size, per cubic foot. In -29- ttling old cracking coil 4" tar line, the average dust concen- 0 2 was 2,322,240 particles per cubic foot. In appearance these iols were clear crystalline, rather rounded, and five microns or in sire. No fibres were observed in any of the dust samples from rntllng operations. After a few weeks or months service, insula- on hot IiEs dries out and appears to disintegrate. This is prob- *bly due. to the fact that such insulation is usually covered with a father-proof material which prevents absorption of moisture from the *ir. CRUSHING SCRAP ASBESTOSt Scrap asbestos insulation, usually the magnesia type, is crushed in a belt-driven Williams crusher to pas3 'through a soreen with one-inch holes or slots, and is then mixed with asbestos to make insulating plaster. This operation, which is a Tory dusty one, is performed by two men, with an average service credit 'of about twelve years. Goggles and MSA. "Comfo" or Willson Dust Respi rators are worn. Considerable dust is produced in breaking up the ''sorap insulation by hand prior to crushing (10,195,200 particles, ten 'microns or less, per cubio foot), and also when feeding the crusher which. is done by shovelling the broken-up pieces into the hopper and Spoking them down with a short wooden stick (14,839,680 particles per roubic foot). Dust counts as high as 27,527,040 particles per cubic 'foot were found in samples taken from over the hopper. These dust con icentrations are dangerously high. About 95? of these particles ore ^sharply angular, orystalline in appearance and five microns or less in 1`sirej 5? are opaque scale-like, six microns or more in size. Crushing ^aorap asbestos is not a steady routine operation, the exposure varying ^from eight hours a month to about twelve hours a wefek. p T CRUSHING OLD CORK INSULATIONt This operation is performed approxi mately twioe a year and takes about twenty or thirty minutes. The in sulation is orushed on a belt-driven Williams crusher, by the same men )who orush the scrap asbestos. This crushed cork is used for insulating lines in the cold settling plant. The average amount of dust produced tis 20,016,178 particles, ten microns or less in size per cubic foot. 'About 80? of the particles are slightly angular, crystalline, in aprpearanoe, and five microns or less in size] 2D% are round, semi-opaque, )ten microns or more. There jure also a large number of. very small black r or dark gr.qy specks. IV - GUNITING OPERATION - What is Gurite and How is it Applied? - Gunite is a mixture of approximately irt (one 94 pound bag) of Portland Cement and two parts (twelve scoop shovels) son sharp sand. The sand and cement are mixed dry, shoveled into the hopper runite machine, using water under about 40-pounds per square inch pressure and )ssed air at thirty to ninety pounds per square inch. It is applied under pres as a 3emi-iTuid, against the surface to be protected (usually process equipment, is, oracking coil soaking drums and storage tanks). In practically every case ^guniting is done, it follows immediately, after the sand blasting job used to the surace. In most cases, the work is performed by the same crew. The indiL holding the gunite nozzle is provided with the same protection as is the for of the sand blast nozzle, and the men tending the gunite machines are pro with respirators and are required to use them while actually handling the sand pnent. This involves mixing the materials and charging them into the machines jwo dustiest parts of a guniting job). Samples taken during these operations '-n ,, a. list counts of particles ten microns or less in size*